• Tunnel and Underground Space
• /
• v.21 no.3
• /
• pp.225-234
• /
• 2011

In this study, an in situ heater test for investigating the thermo-mechanical behavior related to heat flow was carried out. It was the first in situ heater test in Korea. For the test, an adequate design of heater, observation sensors, and data logging system was developed and installed with a consideration of the site condition and the test purposes. It was possible to observe that steep joints are overwhelmingly developed in the test area from a joint survey. The major rock and rock mass properties at the test site could be determined from the thermal and mechanical laboratory tests using the rock cores from the site. From the measured rock temperature distribution, it was possible to observe the influence of the rock joints and the heat flow through tunnel wall. When the heater temperature was maintained as $90^{\circ}C$, the rock temperature at 0.3 m from the heater hole was increased up to $40^{\circ}C$.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2003.07a
• /
• pp.280-286
• /
• 2003

양파의 예건 및 저온저장에 소요되는 노동력 절감과 저장시 발생하는 부패율을 감소시키기 위하여 양파를 한 곳에서 예건과 저온저장할 수 있는 양파 예건ㆍ저온저장 겸용 기계장치를 제작하여 예건 및 저온저장 성능시험을 실시하였다. 주요 연구 결과를 요약하면 다음과 같다. 가 예건과 저온저장을 한 곳에서 할 수 있는 양파 예건ㆍ저온저장 겸용 기계장치는 히트펌프를 이용하여 저장고내의 온도와 습도를 조절할 수 있도록 제작하였다. 나. 예건시 설정온도가 38$^{\circ}C$, 저온저장시 설정온도가 $0^{\circ}C$일 때 온도분포의 표준편차는 각각 0.51, 0.12로 나타났다. 다. 설정온도 및 상대습도를 각각 38$^{\circ}C$, 65%RH로 예건시험을 실시한 결과, 예건 시간은 52시간 소요되었고, 감모율은 0.99-l.79%로 나타났다. 라. 설정온도를 $0^{\circ}C$, 70%RH로 저온저장한 결과, 저장고의 온도는 -0.5-1.5$^{\circ}C$, 저장고의 습도는 70-80%로 나타났다. 마. 관행(자연예건)방법과 시작기로 예건한 양파로 저온저장시험을 실시한 결과, 저장기간 중 감모율은 저장초기부터 일정하게 증가는 경향으로 나타났고, 저장후 20일부터 차이가 나타나기 시작하였으며, 150일 시점에서는 평균 3.16% 차이가 나타났다. 바 저장 중 부패율은 관행의 방법으로 예건한 양파에서 42일째부터 발생하기 시작하여 지속적으로 증가하였고, 시작기로 예건한 양파는 저장후 90일까지는 부패된 양파가 없는 것으로 나타났다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2002.02a
• /
• pp.223-229
• /
• 2002

패드엔팬을 이용하여 물 공급량, 팬 회전속도의 변화에 따른 온실 냉방효과 시험한 결과를 요약하면 다음과 같다. 가. 패드에 흐르는 물 공급량별로 일중 11:00-16:00경에 물 공급량이 분당 60$\ell$이상 공급하면 8.0~9.5$^{\circ}C$의 온도차를 낼 수 있으며, 팬을 1170rpm으로 회전시킬 경우 6.0~9.$0^{\circ}C$의 온도차를 낼 수 있었다. 나. 온실과 팬출구 공기의 온도차는 일중 14:30~16:00 경에 60$\ell$이상의 물을 패드에 공급하는 경우 6.0~7.8$^{\circ}C$ 온도 강하 효과가 있고 팬을 1170rpm으로 회전시킬 경우에는 외기온 28$^{\circ}C$일 때 3$0^{\circ}C$이하로 온도를 강하시킬 수 있었다. 다. 패드에 흘리는 물의량을 60 $\ell$/min 이상을 공급하여 주면 30분당 20~28$\ell$의 물을 증발시킬 수 있다. 배출팬 회전속도가 1170rpm일 경우에 30분당 20~30$\ell$의 물을 증발시키는 것으로 나타났다. 라. 본시험에 사용된 패드엔팬의 흡.배기의 엔탈피변화는 8:30이전에는 흡기가 배기보다 온도가 낮아 엔탈피가 양(+)의 값을 나타났고, 8:30 이후에는 흡기가 배기 보다 온도가 높아 -2.0~-4.OkJ/kg의 엔탈피 차만큼 냉각효과가 있었으며, 냉방효율을 65~80% 수준으로 나타났다. 마. 본시험결과로 패드엔팬의 냉기 공급방식만 개선된다면 이동식인 박스형 패드엔팬도 냉방장치로 사용 가능할 것으로 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.82-89
• /
• 2020

Among the explosives in ammunition, the delay elements, which are used as a retardant, could be influenced by the ambient temperature in the Republic of Korea, where the highest and lowest average annual temperature difference is clear. On the other hand, there has been no domestic research on this. This study examined the linear burning rates of the zirconium-nickel delay elements depending on the ambient temperature in South Korea. The ambient temperature data of South Korea were obtained from the meteorological administration, which was used to set the experimental conditions. The operational time for the K414 fuze was measured by changing the ambient temperature by 10 ℃ from -40 ℃ to 50 ℃. To convert the delay time into the burning rates, the height of the delay element in the K414 fuze body was used. The results indicated that the characteristics of the burning rates for the zirconium-nickel delay element could be estimated as linear, and both the burning rates and the delay time of the zirconium-nickel delay element were 2.73mm/ms and -4.18ms, respectively. This led to an approximately 80 ms delay time difference in the environment where the highest and lowest average annual temperature difference was above 20 ℃. Therefore, the delay time reflecting the ambient temperature should be considered when the test evaluation criteria of zirconium-nickel delay elements are established.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.259-261
• /
• 2012

The effect of high-temperature on the flexural modulus of epoxy resin were evaluated using universal testing machine with 3-point bending and dynamic mechanical analyzer. Temperatures of $30^{\circ}C$, $100^{\circ}C$, and $140^{\circ}C$ were considered for flexural test. The specimens having aspect ratio of 16, 32, and 40 were used. The results of storage modulus from DMA were similar to those from flexural test along with given temperatures. It is found that the flexural modulus increased with increasing aspect ratio and the specimen having aspect ratio of above 32 would be suitable for the evaluation of composite material properties under high temperature condition.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.1
• /
• pp.18-24
• /
• 2013

Recently, the interest is increasing about the eco-friendly concrete. Accordingly, the blast furnace slag(BFS), a by-product of industry is known for improving the durability through compaction in concrete and is expanding the use. The research about BFS in concrete be accomplished frequently. In this study, we should know the hydration characteristic of BFS concrete the through the adiabatic temperature rise test due to the replacement of a variety of BFS. In addition, we produced the regression analysis factors through the test result and analyzied the effect for the replacement of BFS. According to test results, the compressive strength showed a slight degradation or equal and the the adiabatic temperature rise figure and rising factors are went down for rising replacment of BFS. In the future, the study about the adiabatic temperature rise equation for the various replacement of BFS and binder is considered necessary.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.2
• /
• pp.191-197
• /
• 2005

A new method, ToxTemp (TOXcity test based on TEMPerature control) using Ceridaphnia dubia was applied to evaluate the toxicity of insecticide materials and compared with the standard 48 hr acute bioassay. BPMC, diazinon and fenitrothion may cause the inhibition to the biological process in sewage treatment plant and need to detect toxicity within short contact time. The ToxTemp method showed sensitive detection with more shorter contact of 1-1.5 hr time than that of the standard 48 hr acute bioassay. To evaluate toxicity of real wastewater/sewage, the inhibition rate of nitrification and oxygen uptake rate (OUR) using activated sludge, the standard 48hr acute bioassay and ToxTemp method using C. dubia were compared, respectively. On the basis of the inhibition rate of nitrification, the OUR test showed the less sensitive results at the relatively strong toxic sewage. On the other hands, the standard 48hr acute bioassay and ToxTemp method using C. dubia represented the toxicity of each wastewater/sewage with high sensitivity. Even the slightly low (about 1.5%) sensitivity, the ToxTemp method showed the high applicability to the real site of sewage treatment plant.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.28-35
• /
• 2016

The in-situ thermal response test for the design of a ground heat exchanger of geothermal heat pumps have difficulty in predicting the outlet temperature according to the variation of conditions due to the expense and time. This paper suggests a 3-D CFD analysis method to predict the heat transfer performance of vertical type ground heat exchanger, which is mostly used in national, and the outlet temperature and the slope of two in-situ thermal response tests were compared to test the proposed CFD reliability. The results of CFD analysis showed that the outlet temperature was predicted to within $0.5^{\circ}C$ of the actual value and the slope was predicted to within 1.6%. The reliability of the CFD analysis method was confirmed using this process, and the outlet temperature prediction of the two in-situ thermal response tests was obtained by changing ${\pm}20%$ of the flow rate and the effective thermal conductivity conditions, respectively. The results of CFD analysis showed that the outlet temperature of Case 1 was 28.0 (-20%) and $29.6^{\circ}C$ (+20%) for the flow rate variation and $29.6^{\circ}C$ (-20%) and $28.0^{\circ}C$ (+20%) for the effective thermal conductivity variation, and the outlet temperature of Case 2 was 28.4 (-20%) and $29.8^{\circ}C$ (+20%) for the flow rate variation and $29.7^{\circ}C$(-20%) and $28.4^{\circ}C$(+20%) for the effective thermal conductivity variation.

• The Journal of Engineering Geology
• /
• v.26 no.4
• /
• pp.505-513
• /
• 2016

The qualitative distribution of a fractured aquifer was characterized by electrical resistivity surveying as a part of basic groundwater investigation in Jangseong. The results were then used to choose sites for observation wells. The locations and distributions of permeable discontinuities were studied by analyses of temperature logs, a borehole image-processing system (BIPS), and hydraulic pressure testing using a double packer. The pressure test showed that the size of the discontinuities correlated with the Lugeon value and the results of the temperature log. The results show that temperature measurement is an effective method to identify permeable discontinuities, with the temperature difference correlating with the size of the aperture of the discontinuity.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.541-544
• /
• 2008

Recently, due to the increase of high-rise buildings construction, many researches for making harden of concrete earlier and remove of forms faster are being performed to reduce construction period. The purpose of this study is to analysis which mixing condition and curing temperature of early strength concrete. Porperties of concrete by the different factors, such as the type of active admixtures, mineral admixtures, curing temperature, the amount of binder, etc. Through the test of concrete using the different type of admixture, PC type was more excellent than PNS type admixture. The concrete Strength remarkably will be able to confirm that decreases from temperature below 12$^{\circ}C$.